pH: Acid and Alkalis

Question 1

What is an acid?

Answer 1

Anything that produces hydrogen ions in a water solution

Question 2

What is a base?

Answer 2

• Anything that produces hydroxide ions in a water solution
• Accepts H+ ions

Question 3

What example of an acid?

Answer 3

HCl → H+ + Cl-

Question 4

What some common acids?

Answer 4

Citrus fruits, aspirin, vitamin C Vinegar

Question 5

What are some common bases?

Answer 5

Detergents, ammonia
based cleaners

Question 6

What happens when you add acids to water?

Answer 6

The concentration of H3O+ ions increases

Question 7

What is the formula for calculating pH?

Answer 7

𝑝𝐻 = −log_(10)[𝐻+]

Question 8

What is H3O+?

Answer 8

Hydronium ion

Question 9

How can the strength of a weak acid be expressed?

Answer 9

As an equilibrium

Question 10

What is the pH of urine?

Answer 10

6

Question 11

What is the pH of seawater?

Answer 11

8

Question 12

What is the pH of stomach acid?

Answer 12

2

Question 13

What does a high conc. of H+ ions lead to?

Answer 13

Higher pH (acidic)

Question 14

What does a lower conc. of H+ ions lead to?

Answer 14

Lower pH (basic)

Question 15

What are buffer solutions?

Answer 15

• Solutions that resist change to pH when small amounts of acid or base are added
• A chemical that accepts/releases H+ as necessary to keep pH constant

Question 16

What do buffers usually consist of?

Answer 16

Normally consist of a weak acid and a salt (conjugate base) that provides additional A- ions

Question 17

What does carbon dioxide in water produce?

Answer 17

• Carbonic acid
• Bicarbonate
• Carbonate

Question 18

Why is CO2 important?

Answer 18

Because it forms weak acid solutions in water

Question 19

What is Le Chatelier’s Principle?

Answer 19

If a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change to re-establish an equilibrium.

Question 20

When was the river thames severly contaminated of cholera?

Answer 20

1850s

Question 21

When was the ‘Great Stink’ of London?

Answer 21

1858

Question 22

What was the solution the ‘Great Stink’?

Answer 22

Sewage drainage and pumping system

Question 23

What are some water pollution from nutrients?

Answer 23

• Algal blooms
• Eutrophication

Question 24

What is alkalinity?

Answer 24

• Refers to the ability of water to neutralise acid
• Water with high alkalinity has a high capacity to neutralise acid

Question 25

What does alkalinity include?

Answer 25

Includes bicarbonate (HCO3-), carbonate (CO32-), and hydroxide (OH-)

Question 26

What does calcium carbonate precipitation cause?

Answer 26

Forms scales in hot water pipes, heaters, boilers and kettles

Question 27

What is toxic to aquatic life at low concentration?

Answer 27

Metals

Question 28

What is the most common method to remove metal ions from solutions?

Answer 28

• Precipitate them as hydroxide
• Add hydroxide ions